Incandescent electrode vapor electric lamp.



lllivrrnn *rares arent retient1 PETER COOPER HEWITT, OE NEV YORK, N. Y.,ASSIGNOR TO PETER COOPER I-IEWITT, TRUSTEE, OF NEW YORK, N. Y.

INCANDESCENT ELECTRODE VAPOR ELECTRlC LAMP'.

SPECIFIGATIGN forming part of Letters Patent No. 690,952, dated January14, 1902 Application led April 18, 1900. Serial No: 13,290. (No model.)

To @ZZ whom it nt/tty concern:

Be it known that I, PETER COOPER HEWITT, a citizen of the United States,and a resident of New York, in the county of New York and State of Nev7York,have invented certain new and useful Improvements in IncandescentElectrode VaporElectric Lamps, of which the following is-aspecification.

My invention relates to that class of electric-lighting devices in whichelectric energy is transformed intolightbyits action upon gases orvapors inclosed in a suitable chamber with a suitable lightemittingelectrode. In the operation of lamps of the character referred to I havefound that suitable gases having the proper density may be so aiected byelectric currents of moderate electromotive 'force as to yield light andcause the negative electrode to be heated to a high degree ofincandescence. A large portion of the resistance which a lamp of thischaracter offers to the passage of current is at the joint of the gaswith the cathode where the current enters the cathode, the gas alsopresenting considerable resist-ance. By suitably adjusting theseresistances the resistalice at the cathode may be made such that thecathode Will itself become heated to a high degree of incandescence,being itself near the center ofthe source of heat and emitting intenselight. The relative amount of light developed in the vapor-path is smallon account of the relatively short path of the current through the vaporand a certain portion of this vapor-path is occupied by the dark spacewhich surrounds the negative electrode.

In operating lamps with currents of considerable quantity the electriccurrent tends to pass around to the back of the cathode and unlessprevented is liable to fuse the leading in conductors and disintegratethe glass through which they pass. To prevent this, I provide aprotecting-covering for such portions of the electrode, leaving exposedonly those portions at which it is desired that. the current shallenter.

In the accompanying drawings, Figure l illustrates one form of lamp, andFigs. 2 and 3 a modilication.

Referring tothe drawings, l represents the main body of the lamp.

2 represents an electrodein this instance the anode-located in the lowerpart of the lamp, and the cathode is represented at 5. The electrodesmay be made of suitable material-such, for instance, as iron or otherconducting material-but I may make the cathode of some light-etnissivematerial, such as rare earths or mixtures thereof, surrounding' theconductor leading the current toit. The nature of the material of thecathode makes but little difference with respect to its conductivity, aseven When it is of a material which is a non-conductor when cold. thereis suflicient electric leakage into the lainp from the conductor leadinginto it (unless great care be take to prevent it) to start the current,which when started will heat the material by reason of its position atthe negative electrode. The electrode 2 is shown as being seated Withina glass column l0, Which surrounds the leading-in Wire '7; but-theposition of the positive electrode for this style of lamp may be varied.The electrode 5 is shown as being seated Within a tube I4, of porcelainor other suitable material which is a non-conduc tor and retains thisquality when hot and is inert to electrical and chemicalv actions at thetemperature to which it is subjected in the operation of the lamp. Thecylinder 14 is shown as being carried by the stent or column I2 of glassthrough which the leading-in Wire 8 passes. The joints between theelectrode and the porcelain and between the porcelain and the glass aresufliciently tight to prevent the electric current from passing throughthem and reaching the metal parts within, thus forming anelectrically-tight insulation over the conductor vleading through `thewalls of the vessel to the electrode.

With electrodes of the characterdescribed I am able to operate the lampso that the current Will pass to and from the electrodes and beprevented from passing around to the por Vtions near the leadinginconductors.

The lamp illustrated in Fig. l is so construct-ed and its elements areso arranged that in the normal operation of the lamp the cathode Will beheated to a very high tempera ture, becoming itself a light-emittingbody'. In this instance the electrode 5 is located at the center of aglobe l5, the anode 2 being carried in an extension lli'. Gas of theproper density is placed Within the globe. When the current traversesthe lamp, considerable IOO heat is generated at the cathode 5, and thesurrounding gas being, in a measure, at least, a non-conductor of heatthe temperature of the cathode 5 is maintained sufficiently high to belight-emissive. I have found, for instance, that with attenuatednitrogen contained within the chamber and with iron electrodes separateda distance of about one and one-half inches the lamp may be started witha direct current having a pressure of seven hundred and fifty volts orless, and the resistance which the gas oers to the passage of thecurrent and the resistance Which is offered between the gas and thecathode will render the lamp self-governing and pass a definite amountof electrical energy and convert it into light vand heat, the heat beingsufficient to maintain the cathode in a state of incandescence. It hasbeen found that the resist-- ance of a vapor varies inversely with thecnrrent; but in the operation of my lamp in the case of an increase ofcurrent the consequent reduction of resistance in the vapor-path iscompensated for by an increased resistance at the cathode, and viceversa. This particular form of resistance is a phenomenon that takesplace under proper adjustment when thereis no chemical or physicalaction at the negative electrode. The feature of self-regulation isimportant whether the lamp be constructed to yield light merely throughthe instrumentality of the gas or by reason of the incandescence of thenegative electrode, or both. In this lamp the resistances at diiferentpoints may be different at the time of starting from what they are whenthe lamp is running; but by properly adjusting the gas density the lampmay be made to start on the same current that it is designed to operateon.

In Figs. 2 and 3 I have shown the inclosing case in the form of a globe,the cathode being surrounded by an anode 2, made in the form of a ring.The operation of this lamp is essentially the same as already describedwith reference to Fig. 1.

Alamp of the character described in the foregoing specification willregulate its resistance so as to be operative under wide fiuctuations ofelectromotive force. Under increments of current the resistance of theheated cathode may increase; but this increase is compensated for by thechange in resistance of the conducting gas or vapor through wide limits.In this Way a balance is brought about between the elements composingthe luminous portions of the lamp, whereby thelampismadeself-regulating. Whenthelamp is operated by alternatingcurrents, both electrodes may be regarded as cathodes. It is desirablethat the material in the lamp should be such that there shall be nochemical action or physical change in the lamp while in operation.

The invention claimed is l. In an electric lamp consisting of aninclosing chamber, two electrodes within the chamber, an intervening gasWhose resistance decreases with increments of current flowing, and meansfor creating about the cathode a resistanceto the passage of current,the development of heat by the passage of current therethrough beingsufficient to raise the cathode to a light-emitting temperature.

2. An electric lamp consisting of an inclosing chamber, two electrodescontained therein, the cathode being of such material as to becomelight-emissive under the influence of heat without undergoing physicalchange of state, and means for creating such resistance to the passageof current into the cathode as to develop sufficient heat around thecathode to render the cathode incandescent.

3. In an electric lamp having two separated electrodes and an inclosingchamber, a conducting gas or vapor, the Vapor or gas and one of theelectrodes both constituting luminous elements, the resistances of saidluminous elements being mutually corrective under increments of current.

1. In an electric lamp having two separated electrodes, one or both ofwhich constitutes a luminous element, within the lamp, the vapor or gascontained Within the lamp constituting a steadying resistance.

5. In an electric lamp of the character described, a sealed chambercontaining a conducting gas or vapor, a pair of electrodes within saidchamber, a part of said chamber being substantially globe-shaped andhaving the cathode at or near its center, the anode being disposed in aring surrounding the cathode.

6. A gas or vapor electric lamp consisting of a hermetically-sealedinclosing chamber, a ring-shaped anode therein, an exposed cathodeWithin the anode, and a gas or Vapor surrounding the anode and cathode.

7. In a gas or Vapor electric lamp consisting of a hermeticalIy-sealedinclosing chamber and a composite illuminating medium .or body therein,one element of which is a gas or vapor and the other a stationary solidbody.

S. In an electric lamp of the character described, a compositeilluminating medium or body one element of which is solid and adapted tobecome incandescent, the other element being a gas or vapor normallytranslucent and becoming itself luminous under the influence of thecurrent through the lamp, and a hermetically-sealed inclosing chambercontaining the same.

9. The combination with a protected cathode of the character described,of an annular anode surrounding the cathode, substantially as described.

Signed at New York, in the county of New York and State of New York,this 27th day of March, A. D. 1900.

PETER COOPER HEWITT.

Witnesses:

WM. I-I. CAPEL, CHARLES B. HILL.

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